01 - Toss cut eggplant batons lightly with salt and allow them to sit for 10 minutes to extract excess moisture. Rinse thoroughly and pat dry with paper towels.
02 - Heat 3 tablespoons vegetable oil in a wok or large skillet over medium-high heat. Fry eggplant pieces for 6 to 8 minutes, turning to ensure even browning, until golden and tender. Remove and drain on paper towels.
03 - Wipe out residual oil from the pan, leaving about 1 tablespoon. Add ginger, garlic, and chili (if using), and stir-fry for 1 minute until the mixture becomes highly aromatic.
04 - Stir in doubanjiang and cook an additional minute, mixing constantly until the oil turns red and fragrant.
05 - Return fried eggplant to the pan. Pour in soy sauce, dark soy sauce, rice vinegar, sugar, and vegetable stock. Toss gently to ensure thorough coating.
06 - Cover the pan and simmer on low heat for 8 to 10 minutes, allowing eggplant to become exceedingly tender and flavors to harmonize.
07 - Combine cornstarch and water to create a smooth slurry. Pour into the pan and stir for 30 seconds, allowing the sauce to thicken to a glossy finish.
08 - Drizzle sesame oil over the dish and garnish with sliced spring onions before presenting.